Arrangement for rotator units

ABSTRACT

Arrangement for rotator units, especially those which are intended for rotation of excavator buckets. It comprises a motor (27) which, together with a transmission (26, 29) which is coupled to a drive wheel (24) in the chain transmission, is arranged in a movable support (14), which is suspended in the housing (6) in a pivotable manner, but free from fixed connections to the housing. In the transmission there is a drive wheel (24) for a chain transmission, which wheel is connected by means of a drive chain (25) to a driven chain wheel (13) included in a shaft system (12) mounted in the housing. Spring elements (30) are arranged to pivot the movable support (14) in such a way that the chain is held tensioned. The suspension of the movable support in the housing is designed in such a way that deformations of the housing resulting from external force effect are not transmitted to the movable support in a way that would deform the latter.

TECHNICAL FIELD

The following invention relates to an arrangement for rotator units,especially those which are intended for rotation of excavator bucketsand which comprise a housing, a shaft system mounted in the housing withthe output shaft of the unit, a motor arranged in the housing,preferably a hydraulic motor for operating the output shaft, and atransmission system arranged between the motor and the output shaft andcomprising at least one chain transmission.

PRIOR ART

An excavator bucket is arranged on the supporting excavator in such away that it can be pivoted in one plane and be guided into differentpositions in the same plane by means of the excavator arm.Alternatively, equipment other than a bucket, for example equipment forbreaking up asphalt, can be suspended in the same way and thus have thesame movement possibilities. However, in certain work, it isadvantageous if the bucket or the alternative equipment can, inaddition, be pivoted about an axis extending in the said plane. In orderto achieve this, it is known to arrange on the arm of the excavator aso-called rotator unit which is supported by the arm and in turnsupports the equipment in question.

The rotator unit is generally designed with a housing, which hasarrangements for securing to the excavator arm and, in the oppositeposition to these securing arrangements, an output shaft coupling whichis designed for securing of the excavator bucket. In the housing thereare drive arrangements for turning the shaft coupling and, with it, theexcavator bucket or the alternative equipment. In a known embodiment ofsuch a drive arrangement, a hydraulic motor is used for driving theoutput coupling via a transmission.

TECHNICAL PROBLEM

A rotator unit of this type is subject to extremely great forces. Thesearise, on the one hand, because the drive mechanism operates atextremely high load, but primarily because the turning mechanismattempts to hold the bucket in a certain position while it is subjectedto high rotational forces as a result of the movement of the excavatorarm or as a result of other external forces, for example from fallingboulders or masses of earth. In this connection it has proven difficultto dimension the unit in such a way that its functioning is not put atrisk when great forces of this type arise.

SOLUTION

This protection of the drive mechanism against the effect of deformationof the unit is achieved by means of the invention by virtue of the factthat the motor, together with a transmission connected to the latter andbelonging to the transmission system, which transmission is coupled to adrive wheel in the chain transmission, is arranged in a bearing elementwhich is suspended in the housing in a pivotable manner, but free fromfixed connections to the housing, and by virtue of the fact that thesaid drive wheel is connected by means of a drive chain to a drivenchain wheel in the shaft system mounted in the housing, and also byvirtue of the fact that spring elements are arranged to pivot themovable support, by means of force effect, in such a way that the saidchain is held tensioned, in which respect the suspension of the movablesupport in the housing is designed in such a way that deformations ofthe housing resulting from external force effect are not transmitted tothe bearing element in a way that would deform the latter.

ADVANTAGES

The invention provides an arrangement which protects the drive mechanismfrom the effect of deformations of the unit, which can arise in theevent of extremely high, unexpected loads.

The arrangement also provides a protection against those extra stressesand wear which can arise in certain drive parts as a result of incorrectgeometrical conditions on account of especially extensive bearing wear.

DESCRIPTION OF FIGURES

An embodiment of the invention is illustrated in the attached drawings.

FIG. 1 shows a general view of a rotator unit according to the inventiontogether with its attachment to an excavator arm, and the excavatorbucket supported by the unit;

FIG. 2 shows a perspective view of the drive mechanism of the unitwithout the housing;

FIG. 3 shows a front view of the unit, whose housing is partiallyremoved in order to show the internal parts; and

FIG. 4 shows the unit in a side view, from which the drive mechanism canbe seen.

PREFERRED EMBODIMENT

According to FIG. 1, an excavator arm 1 has, at its outer end, anattachment 2 which is pivotable in relation to the arm 1 by means of alinkage 3 and a hydraulic cylinder 4. The arm 1 is movable in itsentirety, and here it is assumed that the machine supporting the arm isan excavator of conventional design. The attachment 2 supports a rotatorunit 5 designed according to the invention, which unit, in FIG. 1, hasthe form of a housing 6 with, on its top side, attachment elements 7which are connected to the attachment 2 of the excavator arm, and anoutput shaft coupling 8. An excavator bucket is attached to the shaftcoupling 8.

The rotator unit 5 has, in the housing 6, a rotation mechanism which isable to rotate the output coupling 8 and, with it, the excavator bucket9 in relation to the housing 6 and, thus, also in relation to theexcavator arm 1. The said drive mechanism is here assumed to be drivenhydraulically, as is indicated by two tubes 10 in FIG. 1. These tubesare connected to a hydraulic pump, as will be described hereinafter.

FIG. 2 shows the turning mechanism of the rotator unit 5. The housing 6is not shown, and so the turning mechanism can be seen in its entirety.

This comprises an output shaft 12 which, in a manner not shown, is indriving connection with the said output coupling 8. A chain wheel 13 isfixed o the shaft. The shaft 12 and, with it, the chain wheel 13 aremounted in the housing 6 in a manner not shown in FIG. 2.

To the side of the chain wheel 13 a bearing element 14 is arranged,which forms a support frame made up of an upper plate 15 and a lowerplate 16, such that an intermediate space is formed between the plates.The plane of the plates extends parallel to the plane of the chain wheel13. They are connected by a securing plate 17 transverse to the plates15 and 16, a shaft bushing 18 and a bearing plate 19. In the movablesupport 14 there is, in both plates 15 and 16, a shaft bearing 22 for ashaft 23 which, when the movable support 14 is introduced into thehousing, runs parallel to the shaft 12 for the chain wheel. Alongsidethe plate 16 the shaft 23 has a chain drive 24 for a chain 25 whichconnects the chain wheel 13 and the chain drive. Furthermore, the shaft23 has a conical gear wheel 26. The two wheels 24 and 13 are connectedin rotationally fixed manner.

Attached to the securing plate 17 is a hydraulic motor 27 whose outputshaft 28 has a gear 29 which is in engagement with the conical gearwheel 26.

A compression spring element 30 is tensioned between the shaft systemfor the chain wheel 13, in which the shaft 12 is included, and themovable support 14, and it seeks to press these two parts away from eachother during tensioning of the chain 25. It can be seen from FIGS. 2-4that the compression spring element 30 bears, on the one hand, against aretainer 34 secured to the housing 6 and, on the other hand, the plate19 on the movable support 14.

The drive mechanism now described is shown in FIG. 3 introduced into thehousing 6, whose one side has, however, been removed in order to showthe mechanism clearly. A part of the chain wheel 13 has also been cutaway in order to show the underlying parts. The retainer 34 forming thesupport for the compression spring element in the shaft system is shown.The support for the other end is, as has been mentioned, the plate 19 onthe movable support 14. As is shown in the figure, the compressionspring element 30 can consist of a number of cup springs which arestacked on top of each other and which are supported by a rod throughthe centre holes of the cups. This rod is mounted in the retainer 34 andthe plate 19, but in such a way that the movable support 14 can moveslightly in the direction towards and from the shaft system of the chainwheel 13. The movable support can thus pivot about the shaft 31 whichextends through the bushing 18 in the movable support and is mounted inthe housing 6. It can also be seen that the hydraulic motor 27 isprovided with feed tubes 36 for which couplings 37 are arranged on topof the housing.

FIG. 4 is a side view of the mechanism inside the housing 6, with itsfront wall in the figure removed. The figure also shows the majority ofthe parts previously described in connection with FIG. 3, and also theshaft coupling 8 which is secured on the shaft 12 and is thus connectedto the chain wheel 13. A bearing, designated 40, for the other end ofthe shaft 12 is also supported by the housing. The shaft 31 in the shaftbushing 18 of the movable support 14 is mounted in the housing 6 at 41and 42, either fixed in supports, in which respect the bushing 18 actsas a pivot bearing, or alternatively directly mounted with its ends inthe housing.

It has been explained above that the drive mechanism comprises a drivesource, the hydraulic motor 27, and an output shaft system centred aboutthe shaft 12 and provided with the coupling 8. In between these twoparts, the driving motor and the driven coupling, the drive mechanismcomprises a transmission, first consisting of the conical geartransmission with the motor gear 29 and the gear wheel 26, and the chaintransmission with the drive 24 and the gear wheel 13. In bothtransmissions a gear reduction of the motor speed and a correspondingincrease in the torque accordingly take place. As has been mentioned, avery high torque is required on the output coupling in the said use.Thus, the forces in the transmission are great and it is important thatthe parts of the transmission co-operate in the correct positions, sothat uneven bearing in the contact surfaces does not arise. However, ithas proven difficult or impossible to ensure the correct positions ifthe incorporated parts are each mounted directly in the housing, becausethe latter is subjected to high deformation forces in the heavy workwhich occurs. These forces lead to such deformations that thetransmission parts can no longer co-operate correctly.

However, these difficulties are avoided in the mechanism according tothe invention. Thus, the hydraulic motor 27 and the transmission towhich it is directly connected, comprising the gear 29 and the gearwheel 26, are mounted in the movable support 14 which is in turn mountedin the housing in such a way that deformations of the housing do notresult in deformations of the movable element. The shaft system for thisfirst transmission is thus not subject to any incorrect positionsresulting from the effect of deformations of the housing.

A correct distance is at all times maintained between the wheels of thechain transmission by means of the spring force from the spring element30. The movable support 14 which constitutes the bearing for the geardrive 24 of the chain transmission is not subject to such greatdeformation movements as it would be if it were directly secured in thehousing. The deformation movements which can occur between the bearingfor the chain drive and for the chain wheel can be absorbed by the chain25 which, to a certain extent, permits such movements. This can takeplace without any excessively great tensional forces arising in thechain, on account of the fact that a correct chain tensioning is at alltimes maintained by means of the compression spring arrangement 30.

Because the chain is loaded by spring forces and not by tensioning ofconnecting wheels in fixed positions, the tensional force of the chaincan also be adapted upon movements and abnormal positions of thesewheels. Such abnormal positions can occur in a chain transmission as aresult of bearing wear, so that the chain wheels can no longer be heldin defined positions but move in the bearings depending on the externalforce effect. If, on the other hand, the chain is tensioned by springforce, it can continually adapt to the momentarily assumed position.

INDUSTRIAL USE

As has emerged from the above, an important embodiment in the inventionis a hydraulic motor-driven rotator unit in which, for the necessarygear reduction of the motor speed, use is made, on the one hand, of atleast one gear transmission and, on the other hand, one chaintransmission. The basic idea of the invention is that the hydraulicmotor is mounted together with the gear transmission in a movablesupport which is not constructed directly together with the housing ofthe unit. The chain transmission runs between a drive wheel belonging tothe movable support and a driven wheel belonging to an output shaftsystem, which is mounted in the housing of the unit. The chaintransmission is held tensioned by means of a spring element between themovable support and the housing of the unit. Deformation as a result ofgreat forces on the housing affect the chain transmission which,however, is at all times held tensioned by means of the spring element,while the movable support is mounted in the housing in such a way thatthe transmission system, which is supported by the latter, is notsubjected to the deformations which the housing may suffer.

In this embodiment and basic principle, the transmission system does nothave to be designed in the manner described and illustrated, in otherwords as a conical transmission, but instead other embodiments are alsoconceivable within the scope of the invention. Thus, it is conceivableto use a transmission with cylindrical gear wheel or with a worm gear,for example. It is also conceivable for the driven wheel of the chaintransmission to be coupled in turn to a transmission system which issupported by the output shaft system, if this transmission system isfree from the housing in such a way that it does not take part indeformations of the latter. It is conceivable, for example, for thechain wheel to form part of a planetary gear, mounted entirely and heldwithin the output shaft system.

I claim:
 1. A rotator unit for the rotation of a workpiece extendingfrom an arm comprising, a housing, support means pivotally mounted insaid housing, motor means mounted in said support means for providingpower to the rotator unit, an output shaft at least partially disposedin said housing and extending from said housing for rotatably engagingsaid workpiece, transmission means mounted in said support meansincluding chain means for transferring power from said motor to saidoutput shaft, and spring means disposed between said housing and saidsupport means for maintaining a predetermined tension on said chainmeans, whereby said transmission means is protected from the effect offorces applied to said housing.
 2. The rotator unit of claim 1, whereinsaid workpiece comprises an excavator bucket.
 3. The rotator unit ofclaim 1, wherein said motor means comprises a hydraulic motor.
 4. Therotator unit of claim 1, wherein said transmission means includes afirst conical gear wheel rotatably coupled to said motor means, a secondconical gear wheel arranged for meshed engagement with said firstconical gear wheel to facilitate radial movement thereto, transmissionshaft means for supporting said second conical gear wheel, saidtransmission shaft means being rotatably mounted to said support means,a first chain drive wheel arranged on said transmission shaft for radialmovement therewith, and a second chain drive wheel spaced from saidfirst chain drive wheel and coupled thereto by said chain means, saidsecond chain drive wheel secured to said output shaft to generaterotational movement thereto.
 5. The rotator unit of claim 1, includingpivot shaft means for pivotally mounting said support means in saidhousing, said pivot shaft means having an axis therethrough, said springmeans including a first end and a second end, and spring support meansmounted on said support means and disposed a spaced distance from saidpivot shaft means, said first end of said spring means being mounted onsaid spring support means and said second end of said spring means beingmounted on said housing.
 6. The rotator unit of claim 5, wherein saidhousing includes fixed retainer means, said second end of said springmeans being mounted on said fixed retainer means, whereby when apredetermined amount of force is exerted upon said output shaft, saidspring means transfers a portion of said force to said spring supportmeans so that said support means will pivot about said axis of saidpivot shaft means.